From patchwork Thu Mar 23 02:55:49 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eddie Kovsky X-Patchwork-Id: 9640397 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id E574A6020B for ; Thu, 23 Mar 2017 02:56:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DDBB52847F for ; Thu, 23 Mar 2017 02:56:41 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D278E28491; Thu, 23 Mar 2017 02:56:41 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 07DC62847F for ; Thu, 23 Mar 2017 02:56:40 +0000 (UTC) Received: (qmail 30051 invoked by uid 550); 23 Mar 2017 02:56:39 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 30033 invoked from network); 23 Mar 2017 02:56:39 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=edkovsky.org; s=mail; t=1490237787; bh=SreN4uU4yktXKlGu70p9B6ac90p+EM2sF+3ANY8UiPQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L2AWG7UwybMg1mWQG1x6JDsph2IFvIsw7CQWHe7TGa/tZxa97rAOhK6dPw1A/sMgM DOouwqQzzToGAOsj7jRtkBXyXyQMeGxnOxfMFZ1clCfmGPcw/tzpJJWoKx9LT7zMq9 fYhQyQGA9hc8utyKQmjVqoZ3E6kBHUUd18US5Too= From: Eddie Kovsky To: jeyu@redhat.com, rusty@rustcorp.com.au, keescook@chromium.org Cc: linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Date: Wed, 22 Mar 2017 20:55:49 -0600 Message-Id: <20170323025549.19588-3-ewk@edkovsky.org> X-Mailer: git-send-email 2.12.1 In-Reply-To: <20170323025549.19588-1-ewk@edkovsky.org> References: <20170323025549.19588-1-ewk@edkovsky.org> X-Virus-Scanned: clamav-milter 0.99.2 at olympus X-Virus-Status: Clean Subject: [kernel-hardening] [PATCH v3 2/2] extable: verify address is read-only X-Virus-Scanned: ClamAV using ClamSMTP Provide a mechanism to check if the address of a variable is const or ro_after_init. It mimics the existing functions that test if an address is inside the kernel's text section. Other functions inside the kernel could then use this capability to verify that their arguments are read-only. Signed-off-by: Eddie Kovsky Acked-by: Kees Cook --- Changes in v3: - Fix missing declaration of is_module_rodata_address() include/linux/kernel.h | 2 ++ kernel/extable.c | 29 +++++++++++++++++++++++++++++ 2 files changed, 31 insertions(+) -- 2.12.0 diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 4c26dc3a8295..51beea39e6c4 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -444,6 +444,8 @@ extern int core_kernel_data(unsigned long addr); extern int __kernel_text_address(unsigned long addr); extern int kernel_text_address(unsigned long addr); extern int func_ptr_is_kernel_text(void *ptr); +extern int core_kernel_ro_data(unsigned long addr); +extern int kernel_ro_address(unsigned long addr); unsigned long int_sqrt(unsigned long); diff --git a/kernel/extable.c b/kernel/extable.c index 2676d7f8baf6..3c3a9f4e6250 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -154,3 +154,32 @@ int func_ptr_is_kernel_text(void *ptr) return 1; return is_module_text_address(addr); } + +/** + * core_kernel_ro_data - Verify address points to read-only section + * @addr: address to test + * + */ +int core_kernel_ro_data(unsigned long addr) +{ + if (addr >= (unsigned long)__start_rodata && + addr < (unsigned long)__end_rodata) + return 1; + + if (addr >= (unsigned long)__start_data_ro_after_init && + addr < (unsigned long)__end_data_ro_after_init) + return 1; + + return 0; +} + +/* Verify that address is const or ro_after_init. */ +int kernel_ro_address(unsigned long addr) +{ + if (core_kernel_ro_data(addr)) + return 1; + if (is_module_rodata_address(addr)) + return 1; + + return 0; +}